Fixed the quad mask in a very specific case and changed saveVTK to write a
specific value for unused nodes instead of the first one which breaks unit
tests depending on the number of ranks used.
Still need to rebaseline some VTK files so the tests pass.

Fixed building with boost < 1.40 by
- removing the saveVTK method from dudley's MeshAdapter completely
(no point introducing it now when we are trying to get rid of it soon)
- adding a helper function to weipa's python layer which can be called from C++
with older boost versions.

escript now supports out-of-tree builds.
All build and test files are now created under a user-definable build_dir
directory.
This also fixes issue 291.
Removed most svn:ignore props since they are no longer required.

-Do not compare mesh variables (like owner, color etc) in the saveVTK tests
since they depend on the number of ranks.
-Fixed a problem where ranks without data samples can't know whether a
reduced mesh is to be used or not.

Phew!
-escript, finley, and dudley now uses weipa's saveVTK implementation
-moved tests from finley to weipa accordingly; dudley still to do
-rebaselined all test files
-fixed a few issues in weipa.saveVTK, e.g. saving metadata without schema
-added a deprecation warning to esys.escript.util.saveVTK
-todo: change doco, tests and other places to use weipa.saveVTK

Prepared weipa to use Silo's HDF5 driver & compression which performs better
than the default PDB. Code is disabled though because NetCDF 4 is currently
interfering (Unidata has been contacted). Added a note about this.

-New VisIt simulation control interface in weipa (uses VisIt's simv2)
-Rewrote restarts.py to be a more generic data manager for restarts and exports
-Removed weipa python file since the functionality is now handled by restarts.py

Reincarnation of the escriptreader as a more flexible escriptexport library:
- can be initialised with instances of escript::Data and Finley_Mesh
- is now MPI aware at the EscriptDataset level including Silo writer
- now uses boost shared pointers
The lib is currently only used by the escriptconvert tool but this is going to
change...